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12. Glossary of Terms

Term             Definition                                      Symbol Units Reference

 Hydrophone      Active electronic device connected to, or to    ---     --- 62127-3 3.12
pre-amplifier    be connected to, a particular hydrophone        p(t)
Instantaneous    and reducing its output impedance NOTE 1                Pa      www.electropedi
                 A hydrophone pre-amplifier requires a                           a.com, 802-01-03
   Acoustic      supply voltage (or supply voltages). NOTE 2
   Pressure      The hydrophone pre-amplifier may have a
                 forward voltage transmission factor of less
                 than one, i.e. it need not necessarily be a
                 voltage amplifier in the strict sense.
                 Pressure at a particular instant in time and
                 at a particular point in an acoustic field,
                 minus the ambient pressure

Instantaneous    In an elastic medium, vector whose              ---     m       www.electropedi
    Particle     terminus is the position of the particle at a   ---             a.com, 802-01-04
                 given instant and whose origin is at the
Displacement     equilibrium position of the particle                    m/s     www.electropedi
Instantaneous    Derivative, with respect to time, of the                        a.com, 802-01-05
                 instantaneous particle displacement
    Particle
   Velocity

  Mechanical     An indictaor related to mechanical effects,      MI     unitless 62359:2010 A.3.1
      Index      derived from measurements of pressure           p-, pr
      Peak-      and frequency                                           MPa     www.electropedi
                 Maximum of the absolute value of the             td             a.com, 802-01-25
 Rarefactional   negative portions of the instantaneous           Ipa
    Acoustic     acoustic pressure waveform in an acoustic        pii    s       www.electropedi
    Pressure     field or in a specified plane during an         ppsi            a.com, 802-01-11
                 acoustic pulse-repetition period. Note –
Pulse Duration   Peak-rarefactional acoustic pressure is                 W/cm²   www.electropedi
                 expressed as a positive number.                                 a.com, 802-01-17
Pulse-Average    1.25 times the interval between the times
    Intensity    when the time integral of the square of the             mJ/cm²  www.electropedi
                 instantaneous acoustic pressure at a point                      a.com, 802-01-16
Pulse-Intensity  reaches 10 % and when it reaches 90 % of
    Integral     its final value Note – The final value of the           Pa²s    www.electropedi
                 time integral of the square of the                              a.com, 802-01-06
Pulse-Pressure-  instantaneous acoustic pressure is the
    Squared      pulse-pressure-squared integral.
    Integral     Quotient of the pulse-intensity integral by
                 the pulse duration at a particular point in an
                 acoustic field
                 Time integral of the instantaneous intensity
                 at a particular point in an acoustic field
                 integrated over the acoustic pulse
                 waveform
                 Time integral of the square of the
                 instantaneous acoustic pressure at a
                 particular point in an acoustic field
                 integrated over the acoustic pulse
                 waveform

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